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BGP: Skip empty path segments in received AS_PATH

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Although RFC 4271 does not forbid empty path segments, they are useless
and some implementations consider them invalid. It is clarified in RFC 7606,
specifying that AS_PATH with empty segment is considered malformed.
This commit is contained in:
Ondrej Zajicek (work) 2016-06-29 14:11:03 +02:00
parent 8f01879c56
commit 775a5a8195
1 changed files with 13 additions and 11 deletions
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24
proto/bgp/attrs.c
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@ -118,7 +118,7 @@ validate_path(struct bgp_proto *p, int as_path, int bs, byte *idata, uint *ileng
{ {
int res = 0; int res = 0;
u8 *a, *dst; u8 *a, *dst;
int len, plen, copy; int len, plen;
dst = a = idata; dst = a = idata;
len = *ilength; len = *ilength;
@ -132,15 +132,20 @@ validate_path(struct bgp_proto *p, int as_path, int bs, byte *idata, uint *ileng
if (len < plen) if (len < plen)
return -1; return -1;
if (a[1] == 0)
{
log(L_WARN "%s: %s_PATH attribute contains empty segment, skipping it",
p->p.name, as_path ? "AS" : "AS4");
goto skip;
}
switch (a[0]) switch (a[0])
{ {
case AS_PATH_SET: case AS_PATH_SET:
copy = 1;
res++; res++;
break; break;
case AS_PATH_SEQUENCE: case AS_PATH_SEQUENCE:
copy = 1;
res += a[1]; res += a[1];
break; break;
@ -154,20 +159,17 @@ validate_path(struct bgp_proto *p, int as_path, int bs, byte *idata, uint *ileng
log(L_WARN "%s: %s_PATH attribute contains AS_CONFED_* segment, skipping segment", log(L_WARN "%s: %s_PATH attribute contains AS_CONFED_* segment, skipping segment",
p->p.name, as_path ? "AS" : "AS4"); p->p.name, as_path ? "AS" : "AS4");
copy = 0; goto skip;
break;
default: default:
return -1; return -1;
} }
if (copy) if (dst != a)
{ memmove(dst, a, plen);
if (dst != a) dst += plen;
memmove(dst, a, plen);
dst += plen;
}
skip:
len -= plen; len -= plen;
a += plen; a += plen;
} }